This invention relates to apparatus for harvesting vegetable matter. More particularly, but not exclusively, it concerns apparatus for harvesting vegetable matter from a body of water.
There are a number of difficulties with the conventional methods of removing, rooting or floating weeds from still and running water. Most current methods rely on blades to cut the weeds. This has a number of disadvantages, one of the most important being that there is a tendency for the cut weeds to regenerate. Another is that it is not always easy to remove the cut fragments from the water. Floating mats of algae present special problems in that they tend to clog the cutting apparatus. They are coped with at present by the use of long rakes which is expensive in labour and not very efficient.
The conventional clearance techniques give rise to the additional problem of how to dispose of the cleared weed material. Usually, it is left to rot on the bank of the water body and this tends to kill the underlying vegetation with consequent weakening of the bank so that the bank often then collapses. The problem is likely to be compounded when a bank-mounted cutter such as a modified back hoe is used.
An alternative to the conventional mechanical clearance methods is chemical treatment. Costs tend to be higher and there is the probability of environmental problems, especially when herbicides are used which are not specific to the weeds to be cleared. In situ break down of the treated plant material tends to release large amounts of nutrients into the water and to consume most of the oxygen available therein. Thus, there is a threat to fish stocks and a tendency for floating mats of algae to develop which reduce penetration of light into the water, effectively inhibiting further plant growth.
In British Patent Application No. 8924148.3, the priority of which is declared in the present patent application, the official search report cited three documents in category `A`, that is, a document relevant as technological background or indicative of the state of the art. Set out below is a brief statement of what it is believed these three documents disclose:
U.S. Pat. No. 3,498,033 discloses a method and apparatus for harvesting sea plants and includes a harvesting vessel with cutting apparatus on an inclined endless belt.
U.S. Pat. No. 3,497,013 discloses apparatus, for use on dry land, to harvest cabbage and lettuce and includes two "co-acting spring biased endless belt means" which grip the vegetables in between.
G.B. Patent Spec. No. 1,531,687 discloses a method apparatus for separating adsorbable hydrocarbons floating on a liquid and includes an absorbant (sic) plastics fibre material, circulating along an endless path.